The Constituents of Cirsium japonicum D.C. var. takaoense KITAMURA Isolation of Two New Flavonoids, Cirsitakaoside (IV) and Cirsitakaogenin (VI)

Abstract

Two new flavone, cirsitakaoside (IV), C₂₃H₂₄O₁₁, mp 246-247°, and cirsitakaogenin (VI), C₁₇H₁₄O₆, mp 259-260°, have been isolated from the fresh leaves of Cirsium japonicum D.C. var. takaoense KITAMURA (Compositae) together with pectolinarin (I). The structures of cirsitakaoside (IV) and cirsitakaogenin (VI) have been determined as 5, 7-dihydroxy-8, 4'-dimethoxyflavone-7-O-β-D-glucoside and 5, 7-dihydroxy-8, 4'-dimethoxyflavone, by chemical degradation and spectral means, respectively.